Concurrency with one thread

ConcurrencyWithOneThread

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Net;
using System.Diagnostics;
using System.Timers;
using System.Collections.Generic;
					
public class Program
{
	static Uri SlowApiUrl = new Uri("http://slowwly.robertomurray.co.uk/delay/2000/url/https://saebamini.com");

	public async static Task Main()
	{
		ThreadPool.SetMinThreads(100, 100);
		ThreadPool.SetMaxThreads(100, 100);
		var timer = new System.Timers.Timer(1000);
		timer.Elapsed += PrintThreadPoolThreads;
		timer.Start();

		var sw = Stopwatch.StartNew();
	//	await TAPSample.DoSequentialAsync();
		await TAPSample.DoConcurrentAsync();

		timer.Stop();
		sw.Stop();
		Console.WriteLine($"The whole thing took {sw.Elapsed.TotalSeconds:F2} seconds");
	}

	public static class TAPSample
	{
		public static async Task DoSequentialAsync()
		{
			for (int i = 0; i < 5; i++)
			{
				var client = new WebClient();
				await client.DownloadStringTaskAsync(SlowApiUrl);
				Console.WriteLine($"Task {i} done");
			}
		}

		public static async Task DoConcurrentAsync()
		{
			var tasks = new List<Task>();
			for (int i = 0; i < 5; i++)
			{
				var client = new WebClient();
				var no = i;
				tasks.Add(client.DownloadStringTaskAsync(SlowApiUrl).ContinueWith(_ => Console.WriteLine($"{no} done")));
			}

			await Task.WhenAll(tasks);
		}
	}

	static void PrintThreadPoolThreads(object sender, ElapsedEventArgs e)
	{
		ThreadPool.GetAvailableThreads(out int availableWorkerThreads, out int availableCpThreads);
		ThreadPool.GetMaxThreads(out int maxWorkerThreads, out int maxCpThreads);
		Console.WriteLine($"{availableWorkerThreads} out of {maxWorkerThreads} worker threads available");
		Console.WriteLine($"{availableCpThreads} out of {maxCpThreads} CP threads available");
	}
}